Just an update here...  I'd like to point out....  I got a DSI prophet REV2 and I made the blues track on Audacity and hacked the codec and used 786khz audio.  It is by no means perfect and made a lot of mistakes, but for scientific purposes....   
So I am unable to encode 768khz FLAC files.....  I guess FLAC doesn't go that high.  I compressed it to 384khz FLAC and then encoded it to 96khz VORBIS:
;but I did encode 768khz 32bit WAV and I will say it is highly noticeable the difference in how smooth the poly sounds in 768khz WAV v. 384khz FLAC.